The present invention relates to a substrate processing method comprising applying a resist solution onto a large substrate such as a liquid crystal display (LCD) substrate and removing the coated resist from the peripheral edge portion of the substrate.
In a manufacturing process of the LCD substrate, a circuit pattern is formed on a glass substrate by a so-called photolithographic process. The photolithographic process including steps of drying a substrate, coating a resist solution on the substrate, exposing the coated resist film with a pattern, and developing the exposed resist film. In such a photolithographic process, it is important to maintain constant atmospheric temperatures of processing units. This is because quality of the coating resist film is strongly affected by the atmospheric temperature. For this reason, the substrate processing apparatus is placed in an air-conditioned clean room. Furthermore, the clean air of the air-conditioned clean room is introduced into the substrate processing apparatus, thereby adjusting processing temperature to a desired temperature (constant temperature) at the time the substrate is coated with a resist. In other words, the same clean air atmosphere as that of the clean room, whose temperature and humidity are controlled, is used as an inner atmosphere of the substrate processing apparatus. In this manner, the processing atmosphere in the coating unit for coating a resist on the substrate can be adjusted to the desired temperature (constant temperature). As a result, a resist film is formed in a film thickness controlled more accurately.
However, the atmosphere of the clean room varies depending upon various factors. Due to-the influences of the various factors, the inner atmosphere (temperature and humidity) of the substrate processing apparatus changes. As a result, a resist film is formed in uneven thickness. In addition, the processing apparatus for the LCD substrate is large since the LCD substrate is larger than a semiconductor wafer. As a result, the atmosphere of the apparatus is not uniform in temperature and humidity. In other words, temperature and humidity of the atmosphere significantly differs depending upon sections of the apparatus. In particular, if the atmospheric temperature of the coating unit changes, the resultant resist film is formed in a thickness which deviates significantly from a desired value and formed in an extremely non-uniform thickness, producing a coating defect. Consequently, the yield of a final product tends to decrease.
The aforementioned temperature change of the atmosphere is one of reasons for the following phenomenon called xe2x80x9cindirectly influenced markxe2x80x9d. When a temperature change occurs between a contact member in contact with the substrate at its lower surface and the substrate when the substrate is processed or transported, the resist film formed on the upper surface of the substrate corresponding to the contact site by the contact member quantitatively and qualitatively differs from the resist film of the remainder portion.
In generally known methods, the photolithographic process is applied to a substrate horizontally fixed on a table or to a spinning substrate. In the case of the LCD substrate, the LCD substrate is adsorbed and held by a plurality of adsorption members provided on the upper surface of the table. More specifically, these adsorption members adsorb the rear surface of the substrate, thereby fixing the substrate on the table.
The table having adsorption members is used in a process of removing a coated resist from the peripheral edge surface of the substrate. In the process for removing a peripheral-edge resist, a solvent (e.g., thinner) is supplied to the peripheral edge portion of the substrate from a nozzle while moving the nozzle along the peripheral edge portion of the substrate adsorbed onto the table. In this case, the resist dissolved in the solvent is removed by vacuum-evacuation of the substrate peripheral edge portion. Note that the adsorption members keep adsorbing the rear surface of the substrate during the process.
In a conventionally-used apparatus, even if such a removal process is applied, the resist coating film formed on the upper surface of the substrate whose lower surface is adsorbed by the adsorption members differs in quantity and quality from that formed on the upper surface of the substrate whose rear surface is not adsorbed by the adsorption members. More specifically, marks are made on the surface of the substrate by indirect influence of the adsorption members attached on the rear surface (hereinafter referred to as xe2x80x9cindirectly influenced markxe2x80x9d). The indirectly influenced mark of this type have a negative effect on the light-exposure processing and the developing performed in later steps. As a result, the yield of the final LCD product may decrease.
An object of the present invention is to provide a substrate processing method capable of preventing occurrence of coating defects and xe2x80x9cindirectly influenced markxe2x80x9d.
According to the present invention, there is provided a method of processing a substrate for forming a coating film on a substrate comprising the steps of:
(a) mounting a substrate on a temperature controlling means which is capable of having a thermal influence on the substrate, and controlling temperature of the substrate by the temperature controlling means;
(b) controlling temperature of a coating solution to be supplied to the substrate;
(c) controlling temperature of a contact member in contact with the substrate when the substrate is transported or held;
(d) detecting temperature of an atmosphere of a process space for applying the coating solution to the substrate;
(e) setting a desired temperature for forming a coating film on a substrate;
(f) controlling a temperature controlling operation of at least step (c) on the basis of the desired temperature set in the step (e) and the temperature detected in the step (d); and
(g) applying the coating solution to the substrate.
It is preferable that, in the step (g), the solvent controlled in temperature in the step (b) be applied to the substrate.
It is also preferable that, in the step (c), a spin chuck for rotatably holding the substrate be used as the contact member.
It is further preferable that, in the step (c), the process space surrounding the substrate mounted on the spin chuck be closed.
It is still preferable that, in the step (d), temperature of a fluid body flowing through a discharge passage be detected.
The method of the present invention is desirable to further comprise a step of setting temperature controlling conditions which provide a constant relationship between a temperature TT for the contact member in contact with the substrate, a temperature TH of the substrate, temperature TR of the coating solution, and a temperature TA of the atmosphere within the process space in a period from a previous step of applying the coating solution to the substrate until the coating film is cured.
As a result of intensive studies conducted by the present inventors, it was found that the xe2x80x9cindirectly influenced markxe2x80x9d is likely to increase in size as the adsorption time of the substrate by the adsorption member gets longer. To describe more specifically, it is known that when a regional difference in temperature of the resist coating film formed on the substrate is 1.5xc2x0 C. or more, the indirectly influenced mark is produced.
According to the present invention, it is possible to control temperature of each section of the process apparatus on the basis of an atmospheric temperature (detected temperature) of a process space and a desired temperature (preset temperature). Consequently, it is possible to prevent occurrence of coating defects and xe2x80x9cindirectly influenced markxe2x80x9d before happening even if the temperature of the coating unit changes. In other words, temperatures of the substrate, the coating solution, the solvent, contact members (including a spin chuck, lift pins, and a transfer arm holder which are in direct contact with the substrate) are individually controlled. Therefore, influences from a temperature change of the external environment (clean room) can be overcome. As a result, the resist film can be formed in a more accurately controlled thickness. Simultaneously, the occurrence of the indirectly influenced mark is prevented.
According to the present invention, there is provided a method for processing a substrate for removing an unnecessary portion of a coating film formed on a substrate, comprising the steps:
(A) adsorbing and holding the substrate by a plurality of adsorption sites each being arranged along a corresponding peripheral side edge of an upper surface of a table;
(B) sucking and discharging a coating film dissolved in a solvent simultaneously with supplying the solvent to each of the substrate peripheral edge portions from a corresponding solvent nozzle while moving a plurality of solvent nozzles along the corresponding peripheral edge portions of the substrate; and
(C) switching an adsorption maintaining operation to an adsorption canceling operation of the adsorption sites individually or in a unit of group, in at least the step (B).
According to aspects of the present invention, the adsorption time of each of adsorption sites can be reduced by switching operation of the adsorption sites in an on-off manner. Consequently, the occurrence of the indirectly influenced mark is prevented.
According to the present invention, the adsorption time of each of adsorption sites can be reduced by switching operation of the adsorption sites in an on-off manner. Therefore, the indirectly influenced mark is prevented by the switching operation.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.